Mechanics of a gaseous film barrier to lubricant wetting of elastohydrodynamically lubricated conjunctions

Two analytical models, one based on simple hydrodynamic lubrication and the other on soft elastohydrodynamic lubrication, are presented and compared to delineate the dominant physical parameters that govern the mechanics of a gaseous film between a small droplet of lubricant and the outer race of a ball bearing. Both models are based on the balance of gravity forces, air drag forces, and air film lubrication forces and incorporate a drag coefficient C sub D and a lubrication coefficient C sub L to be determined from experiment. The soft elastohydrodynamic lubrication (EHL) model considers the effects of droplet deformation and solid-surface geometry; the simpler hydrodynamic lubrication (HL) model assumes that the droplet remains essentially spherical. The droplet's angular position depended primarily on the ratio of gas inertia to droplet gravity forces and on the gas Reynolds number and weakly on the ratio of droplet gravity forces to surface tension forces (Bond number) and geometric ratios for the soft EHL. An experimental configuration in which an oil droplet is supported by an air film on the rotating outer race of a ball bearing within a pressure-controlled chamber produced measurements of droplet angular position as a function of outer-race velocity droplet size and type, and chamber pressure

Transformation of Public Space into Private Space during the World Soccer Championship 2006 in Germany

In this article, the commercial use of sports venues is examined as a means to explore the commercialization and privatization of urban spaces through marketing and sponsorship at public events. It reveals how Berlin was dominated by commercialization during the World Soccer Championship 2006 in Germany in several ways

The impact of Islamic culture on public urban space in Berlin, Germany

Since decades immigrants have come to Germany and they have changed the appearance, culture and urban experience in cities and neighbourhoods in a significant way. There are certain neighbourhoods like Kreuzberg, Wedding and Neukolln in Berlin that have gained a new identity through the mix and interchange of people with different backgrounds - visible in the context of urban space. There are three main topics that will be analysed within this context: Small family businesses and their influence on their surrounding space; form and use of public space; and significant architecture types like mosques and their role for urban space

Thermo-micro-mechanical simulation of bulk metal forming processes

The newly proposed microstructural constitutive model for polycrystal viscoplasticity in cold and warm regimes (Motaman and Prahl, 2019), is implemented as a microstructural solver via user-defined material subroutine in a finite element (FE) software. Addition of the microstructural solver to the default thermal and mechanical solvers of a standard FE package enabled coupled thermo-micro-mechanical or thermal-microstructural-mechanical (TMM) simulation of cold and warm bulk metal forming processes. The microstructural solver, which incrementally calculates the evolution of microstructural state variables (MSVs) and their correlation to the thermal and mechanical variables, is implemented based on the constitutive theory of isotropic hypoelasto-viscoplastic (HEVP) finite (large) strain/deformation. The numerical integration and algorithmic procedure of the FE implementation are explained in detail. Then, the viability of this approach is shown for (TMM-) FE simulation of an industrial multistep warm forging

Navier-Stokes cascade analysis with a stiff Kappa-Epsilon turbulence solver

The two dimensional, compressible, thin layer Navier-Stokes equations with the Baldwin-Lomax turbulence model and the kinetic energy-energy dissipation (k-epsilon) model are solved numerically to simulate the flow through a cascade. The governing equations are solved for the entire flow domain, without the boundary layer assumptions. The stiffness of the k-epsilon equations is discussed. A semi-implicit, Runge-Kutta, time-marching scheme is developed to solve the k-epsilon equations. The impact of the k-epsilon solver on the explicit Runge-Kutta Navier-Stokes solver is discussed. Numerical solutions are presented for two dimensional turbulent flow over a flat plate and a double circular arc cascade and compared with experimental data

On the numerical solution of the dynamically loaded hydrodynamic lubrication of the point contact problem

The transient analysis of hydrodynamic lubrication of a point-contact is presented. A body-fitted coordinate system is introduced to transform the physical domain to a rectangular computational domain, enabling the use of the Newton-Raphson method for determining pressures and locating the cavitation boundary, where the Reynolds boundary condition is specified. In order to obtain the transient solution, an explicit Euler method is used to effect a time march. The transient dynamic load is a sinusoidal function of time with frequency, fractional loading, and mean load as parameters. Results include the variation of the minimum film thickness and phase-lag with time as functions of excitation frequency. The results are compared with the analytic solution to the transient step bearing problem with the same dynamic loading function. The similarities of the results suggest an approximate model of the point contact minimum film thickness solution

Impact of the Great Recession on Total Employment and Unemployment Rates in the U.S.

Color poster with text, images, maps, and tables.The economic downturn of 2008-09 was so severe that it has become known as the Great Recession, and by most accounts the subsequent recovery has been relatively slow. The most basic method of judging the severity of a recession and the success of a recovery is to look at labor market information. In particular, the unemployment rate and the number of jobs (total employment) are often used for this purpose. This study presents data from the U.S. Bureau of Labor Statistics for 2007, 2009 and 2011 using maps to describe the recession and recovery at a national level as well as compare the effects across states.University of Wisconsin--Eau Claire Office of Research and Sponsored Programs; Xcel Energy-Eau Claire; Northwestern Bank-Chippewa Falls